We recommend using
Dali and JPA
Perspective with EclipseUML, and not only the modeling perspective, in
order to take the full advantage of the tight UML integration within
Eclipse with JPA. For example, the reverse of existing
Database is gerated by Dali, then EclipseUML upload all information in
the class diagram. It allows to extend the model and generate metamodel
+ Java Annotation in the code. Finally powerfull mappers such as
toplink or Hibernate can generate code for Oracle, MySQL etc...

1. To activate the JPA
perspective you need to click on the
Open Perspective icon
in the upper right corner of Eclipse.

Select
Other...

Select
JPA Development

2.
Immediately after the click on the OK
button, Eclipse switch to JPA Perspective.
Go in the Package Explorer and create a JPA project, then add a package
to your src in order to activate the class diagram creation.You can not create class diagram if
you don't create a package.

Click on the package and select New UML Diagram > UML Class Diagram

You Class Diagram has been created
inside the JPA Perspective.

3. In order to
activate the Database
preferences inside EclipseUML, click on the class diagram backgorund
and select Persistence Development
>
JPA.

Once the JPA menu is selected, the JPA toolbar is immediately
activated in the Class diagram